Reverse osmosis systems are commonly used for removing impurities from water, such as drinking water. A conventional reverse osmosis system includes a reverse osmosis filter having a reverse osmosis membrane. Feed water is supplied to the filter, and the filter delivers filtered product water having a reduced impurity content. Not all of the feed water supplied to the filter passes through the reverse osmosis membrane, and this unfiltered water, or brine, can be discharged to drain or a portion of it can be recycled through the filter.
To increase the throughput, i.e., the volume of product water, it is known to employ a pump to increase the pressure of the feed water supplied to the reverse osmosis filter. A conventional electric motor driven pump is used for this purpose. Motor driven pumps increase installation costs by requiring electrical wiring to the pump. In addition, they are subject to higher operational costs due to the cost of electricity and the cost of maintaining and repairing or replacing the electrical motor.